Embedded 3D printing of microstructured multi-material composites

Abstract

Additive manufacturing could open new opportunities in the design of advanced composites and multi-material devices. However, when it comes to the combination of inorganic materials, it is difficult to achieve the structural control demanded by many advanced applications. To address this challenge, we have formulated a self-healing ceramic gel that enables the movement of a printing nozzle in its interior. After a heat treatment, the gel forms a defect-free ceramic encapsulating the printed structure. We have used this technique to print sacrificial lightweight graphite structures as well as dense steel frameworks within an alumina ceramic. The graphite is used to generate complex microchannel arrays, whereas the introduction of auxetic steel structures results in works of fracture 50% greater than those obtained with simple fiber arrays and orders of magnitude above the fracture energy of the matrix. These results suggest that embedded 3D printing can open the way to implement new composite designs.